I only have experiance with the 4.6L engine used in the crown vics, and to my understaning the long block is the same. But I have never heard of these failing until I read up here about the 5.4L cam phaser issues. I looks like the roller followers are the same design.

So does the 4.6L have issues with the roller rockers?

 

The 3 valve 4.6 does which is used in 09-10 trucks, 06-10 explorers, and 05-10 mustangs

 

But the 2 valves do not? I fail to understand this.....

 

The 3 valve does tend to have more rocker failures. I guess maybe because of cheaper materials used to make them, or because of insufficient oil flow on 3 valve heads. The 2 valve is not immune to this issue, though. I recently saw a thread with a 4.6 in about the same year as yours and had a noise coming from the top end and it turned out to be a seized up roller rocker and scored the cam.

 

The 2valve rocker is a lot larger with a larger roller and bearing. They only need 8 per side vs 12 per side. They both get good lube imo the lube is not the problem with the 3 valve. The roller and bearing is physically smaller so it spins faster and has less surface area on the bearing to distribute the load than the 2 valve.